Showing papers on "Curie–Weiss law published in 1979"
TL;DR: In this article, the magnetic properties of rare earth copper compounds were determined from the values of anisotropic paramagnetic Curie temperatures on the basis of the molecular field theory, which are in agreement with those evaluated from a point charge model.
Abstract: Measurements of magnetization and susceptibility have been made on single crystals of heavy rare earth copper compounds, RCu 2 . All these compounds show metamagnetism with a relative low critical field at 4.2 K. The paramagnetic Curie temperatures along each principal axis are anisotropic. The crystal field parameters V 2 0 and V 2 2 are determined from the values of anisotropic paramagnetic Curie temperatures on the basis of the molecular field theory. These values are in agreement with those evaluated from a point charge model. The neutron diffraction measurements on a TbCu 2 single crystal confirm the collinear magnetic structure.
70 citations
TL;DR: Magnetic measurements on Al-flux grown EuB6 crystals show that this material orders ferromagnetically with a transition temperature Tc=13.7 K.
Abstract: Magnetic measurements on Al‐flux grown EuB6 crystals show that this material orders ferromagnetically with a transition temperature Tc=13.7 K. The effective moment derived from paramagnetic susceptibility measurements gives μeff=7.76 μB, and the saturation magnetization extrapolated to 0 K is within 10% of the theoretical value of 7 μB expected for Eu+2. The magnetic order, however, cannot be that of a simple colinear ferromagnet because the magnetic specific heat in zero applied magnetic field shows a broad maximum centered about 9 K rather than the expected λ‐like anomaly at 13.7 K. Finally, transport measurements suggest that EuB6 is an intrinsic semimental.
69 citations
TL;DR: In this paper, the ternary rare earth compound NdRh 4 B 4 has been studied by means of critical field, low temperature heat capacity, and static magnetic susceptibility measurements, and features in the upper critical field and heat capacity data at 1.31 K and 0.89 K suggest the occurrence of long-range magnetic order in the superconducting state.
65 citations
TL;DR: In this paper, it was shown that the C15-type structure persists to at least UFe1.7 and that the magnetic properties vary regularly with changes in stoichiometry.
55 citations
TL;DR: The magnetic properties of the pseudobinary Zr(Fe1-xCox)2 system were studied by magnetic, Mossbauer and low-temperature specific heat measurements as discussed by the authors.
Abstract: The magnetic properties of the pseudobinary Zr(Fe1-xCox)2 system were studied by magnetic, Mossbauer and low-temperature specific heat measurements. ZrFe2 is a strong ferromagnet, whereas ZrCo2 shows Pauli paramagnetism. Both the spontaneous magnetisation and the Curie temperature decrease with increasing Co content and the system becomes a weak ferromagnet for x=0.3 and 0.4, where remarkable Invar anomalies are observed. In x=0.5 approximately 0.7, the system shows micromagnetism. No spin freezing has been detected down to 4.2K for x-0.8 approximately 1.0. It has been shown that ferromagnetism is markedly enhanced by excess Fe and Co atoms which occupy Zr sites.
47 citations
TL;DR: In this paper, X-ray, electrical and magnetic measurements have been made on several quarternary chalcogenides of the type Cu2IBIICIVX4 with BII = Zn, Mn, Fe, Co; CIV = Si, Ge, Sn; X = S, Se.
46 citations
TL;DR: In this article, measurements of the magnetic susceptibility of the R2In compounds from 4.2 to 270 K have been made and all compounds except Y2In and Sm2In exhibit Curie-Weiss behavior at high temperatures with effective magnetic moments agreeing reasonably well with the free-ion 3+ picture modified by RKKY exchange except for Gd2In, which gives an unusually high value for the effective moment.
Abstract: Measurements of the magnetic susceptibility of the R2In compounds from 4.2 to 270 K have been made. All compounds except Y2In and Sm2In exhibit Curie‐Weiss behavior at high temperatures with effective magnetic moments agreeing reasonably well with the free‐ion 3+ picture modified by RKKY exchange except for Gd2In, which gives an unusually high value for the effective moment. With the exception of Y2In all other members exhibit susceptibility maxima. Gd2In, Tb2In, and Dy2In order antiferromagnetically. Gd2In is a metamagnetic compound. For the three compounds Ho2In, Er2In, and Tm2In there is no indication of their type of ordering at low temperatures. The isotherm at 4.2 K of Nd2In shows a ferromagnetic or ferrimagnetic behavior.
40 citations
TL;DR: In this article, the hyperfine fields and Curie temperatures of the Heusler alloys (X2MnZ) were analyzed and it was shown that the s−conduction electron polarization (sCEP) is essentially independent of the X or Z element.
Abstract: The hyperfine fields and Curie temperatures of the Heusler alloys (X2MnZ) are analyzed and show that: (1) The s‐conduction electron polarization (sCEP) is essentially independent of the X or Z element. It is also independent of the difference in the number of valence electrons between a Cd impurity, at a Z site and the Z atom it replaces. This behavior is in contradiction to the basic assumptions made in the charge perturbation models for hyperfine fields but in agreement with the assumptions of the volume overlap model. (2) The behavior of the Curie temperature shows that it is the d‐conduction electron polarization not the sCEP that dominates the coupling between the magnetic Mn atoms in the ferromagnetic Heusler alloys.
38 citations
TL;DR: Magnetic susceptibility measurements in the temperature range 4.2-300°K for the MU8X17 type chalcogenides, where M is a 3d transition metal or Mg, and X = S or Se, were carried out.
28 citations
TL;DR: In this article, a Landau-Ginzburg theory for macroscopically inhomogeneous ferromagnetic systems involving only one magnetic species is developed in terms of the local densities of the magnetic atoms.
Abstract: A Landau-Ginzburg theory for macroscopically inhomogeneous ferromagnetic systems involving only one magnetic species is developed in terms of the local densities of the magnetic atoms. For a nearly homogeneous system the shifts of the Curie temperatures due to the inhomogeneities are discussed. The paramagnetic susceptibility and the spontaneous magnetisation are also considered.
26 citations
TL;DR: In this paper, a study of the dependence of the elastic behavior of polycrystalline mixed cobalt-zinc ferrites on temperature and magnetic field has been made using a composite oscillator method.
Abstract: A study of the dependence of the elastic behaviour of polycrystalline mixed cobalt-zinc ferrites on temperature and magnetic field has been made using a composite oscillator method. As the temperature is increased the Young's modulus attains a minimum at a temperature below the Curie point. Thereafter it exhibits a positive temperature coefficient up to the Curie point and decreases with further increase of temperature. This anomalous behaviour has been explained in terms of magnetic anisotropy energy. In the case of cobalt ferrite and Co 0.6 Zn 0.4 Fe 2 O 4 the Young's modulus is found first to decrease and later to increase with increasing magnetic field, finally becoming constant at the saturation field. In contrast, in the case of Co 0.4 Zn 0.6 Fe 2 O 4 and Co 0.2 Zn 0.8 Fe 2 O 4 the Young's modulus does not show an initial decrease but increases with increasing magnetic field. The observed ΔE effect in the case of cobalt ferrite has been interpreted in terms of two domain processes, i.e. domain rotation against uniaxial strain anisotropy and the movement of 90° boundary walls. A study of the effect of the simultaneous application of temperature and magnetic field on the elastic behaviour of mixed cobalt-zinc ferrites has also been carried out.
TL;DR: In this paper, the phase transition with respect to a magnetic field from a nonmagnetic (h Δ) state at zero temperature in a one-dimensional electron system with attractive interaction is studied.
Abstract: The phase transition with respect to a magnetic field from a nonmagnetic (h Δ) state at zero temperature in a one-dimensional electron system with attractive interaction is studied. An exact solution of the Luther-Emery model for a particular value of the coupling constant U‖=−6πVF/5 is used. The transition shows up as the appearance of a gapless mode in the spin-excitation spectrum at the critical field hc=Δ, where Δ is the gap in the spectrum in zero field. The behavior of various correlation functions and the low-temperature anomalies of the thermodynamic quantities are calculated. Some questions related to a quantitative description of the transition in the Luther-Emery model for U‖≠−6πVF/5, and also in other models, are discussed.
TL;DR: The magnetic phase diagram of Ho2O2SO4 (Bext ∥ a) was derived from magnetization and susceptibility measurements as mentioned in this paper, and the magnetization of these phases are 1 3 of the respective saturation values.
TL;DR: For a spin one-half Ising ferromagnet with two-dimensional quadratic lattice, the effects of the apparent three spin interaction, which is reduced effectively to the bilinear exchange interaction between next nearest neighbors, on the Curie temperature, magnetization and the magnetic specific heat have been calculated with the use of Bethe-Peierls theory as mentioned in this paper.
Abstract: For a spin one-half Ising ferromagnet with two-dimensional quadratic lattice, the effects of the apparent three spin interaction, which is reduced effectively to the bilinear exchange interaction between next nearest neighbors, on the Curie temperature, magnetization and the magnetic specific heat have been calculated with the use of Bethe-Peierls theory. The ferromagnetic order is shown to become unstable when the ratio of the three spin interaction to the bilinear exchange interaction amounts to -1/3. Also it is pointed out that the three spin interaction gives significant changes on the Curie temperature and on the temperature dependences of the magnetization and the magnetic specific heat.
TL;DR: In this paper, a detailed study of the evolution of the magnetisation in mixed CoS2-xSex compounds with various selenium concentrations from pure ferromagnetic CoS 2 to pure paramagnetic CoSe2 is presented.
Abstract: The authors present a detailed study of the evolution of the magnetisation in mixed CoS2-xSex compounds with various selenium concentrations from pure ferromagnetic CoS2 to pure paramagnetic CoSe2. They show that at low temperature these compounds are of three types: (i) below x=0.28, the compounds exhibit normal ferromagnetic behaviour with a magnetic moment of about 0.9 mu B cobalt atom; (ii) 0.28
TL;DR: The magnetic susceptibility and Knight shift of the compounds CeCu 4 and CeCu 5 have been measured over the temperature ranges 80-800 and 140-400 K, respectively, in this article, and the most important contributions to the magnetic susceptibility are the Curie-Weiss term, expressing the paramagnetism of localized ƒ-electrons, and a temperature independent term.
TL;DR: In this paper, a correlation was found between the Curie temperature and the magnetic moment per iron atom determined in previous neutron-diffraction experiments, and the overall magnetic behavior of the compounds studied implies the presence of local magnetic moments.
TL;DR: The magnetically hard Fe2B has a higher Curie temperature than the magnetically soft Fe3Si, which leads to unusual thermomagnetic behavior during cooling in low fields as discussed by the authors.
Abstract: The chill‐cast alloy Fe75Si15B10 consists of submicron Fe2B rods in a Fe3Si matrix. The magnetically ’’hard’’ Fe2B has a higher Curie temperature than the magnetically ’’soft’’ Fe3Si, which leads to unusual thermomagnetic behavior during cooling in low fields. When the thermoremanent magnetization (TRM) of the Fe2B produces a demagnetizing field greater than the applied field, the Fe3Si magnetizes opposite to the applied field, thereby reducing the net internal field. However, the magnetic heterogeneity of the sample prevents the net internal field from reaching zero. Significant magnetization changes are also noted in the temperature range where the magnetic anisotropy of Fe2B changes from easy‐axis to easy‐plane.
TL;DR: Magnetization and susceptibility measurements performed on single crystal Erbium Iron Garnet (ErIG) are presented over the temperature range 4.2-6O0 K in a field up to 30 kOe applied along the [111] direction as discussed by the authors.
Abstract: Magnetization and susceptibility measurements performed on single crystal Erbium Iron Garnet (ErIG) are presented over the temperature range 4.2–6O0 K in a field up to 30 kOe applied along the [111] direction. Important differences from polycrystalline sample results are obtained. The magnetic susceptibility follows a Curie Weiss law; but two values of the paramagnetic Curie temperature and of the Curie constant in the two temperature ranges separated by the compensation temperature are found. At low temperature, the exchange interactions between Er3+ ions are not negligible compared to the iron–rare earth interactions. The molecular field coefficient which represents these last interactions is found to be strongly temperature dependent.
TL;DR: The electrical resistivity and magnetization of V x Cr 3− x S 4 (x = 0.0 - 1.0) have been measured in this article, where weak ferromagnetic moments are observed at low temperatures for x ≠ 0.
TL;DR: In this paper, the magnetic response of an iron whisker grown with its long axis parallel to the [111] direction has been measured up to and through the Curie temperature, and the anisotropy constant is found from the response in the range of fields between that necessary to bring the magnetization in the central cross section of the whisker to Ms/sqrt(3) and that to reach Ms.
Abstract: The magnetic response of an iron whisker grown with its long axis parallel to the [111] direction has been measured up to and through the Curie temperature. The anisotropy constant is found from the response in the range of fields between that necessary to bring the magnetization in the central cross section of the whisker to Ms/sqrt(3) and that to reach Ms. We extract a field proportional to K1/Ms and analyze its dependence on Ms and on temperature. The results indicate that K1/Ms∼Msn with n=3.11±.05 for the temperature range 0.0005< (Tc−T)/Tc<0.002 with n increasing at lower temperatures. The sensitivity of the method permits the extraction of K1 values over five orders of magnitude.
TL;DR: The magnetic measurements on Y(FecAl1-c)2 compounds with c>or=0.80 showed that, at temperatures above but close to the Curie points, the susceptibility obeys a relation of the form chi -1 varies as (T-Tc)gamma where gamma = 1.34+or-0.05 as discussed by the authors.
Abstract: The magnetic measurements on Y(FecAl1-c)2 compounds with c>or=0.80 show that, at temperatures above but close to the Curie points, the susceptibility obeys a relation of the form chi -1 varies as (T-Tc)gamma where gamma =1.34+or-0.05. At higher temperatures the reciprocal susceptibility follows a Curie-Weiss behaviour. The ratio between the number of spins determined from paramagnetic data and the saturation magnetisation is a function of the Curie temperature. The spectroscopic splitting factor g=2.12+or-0.03 is not dependent on temperature or composition.
TL;DR: By using a high-field solenoid, the force on a magnetic sample resulting from a field gradient becomes large and measurements using the Faraday (or Curie) method are greatly simplified.
Abstract: By using a high‐field solenoid, the force on a magnetic sample resulting from a field gradient becomes large and measurements using the Faraday (or Curie) method are greatly simplified. By using an electronic analog dividing circuit, curves of magnetic moment or susceptibility versus field or temperature can be quickly and easily recorded. Various examples are given.
TL;DR: In this article, magnetization measurements on sputter deposited amorphous MnSi have been carried out and it has been shown that the magnetic susceptibility of the alloy follows a Curie Weiss law at high temperatures, but deviates considerably from it at lower temperatures.
Abstract: We report magnetization measurements on sputter deposited amorphous MnSi. Above 100 K the susceptibility follows a Curie Weiss law, but deviates considerably from it at lower temperatures. At 21 K the alloy becomes a spin‐glass. Comparison with the properties of crystalline MnSi suggests that the two systems have very similar interactions and that amorphous MnSi, like crystalline MnSi, is probably itinerant.
TL;DR: The magnetic susceptibility data as a function of temperature for a thin film prepared by rf•sputtering from an Fe3O4 target in an O2•Ar atmosphere was reported in this article.
Abstract: We report Mossbauer and magnetic susceptibility data as a function of temperature for a thin film prepared by rf‐sputtering from an Fe3O4 target in an O2‐Ar atmosphere. Powder X‐ray diffraction data shows very broad bands at d = 2.7, 2.0 and 1.5 A. The magnetic susceptibility data as a function of temperature may be divided into three regions. The low temperature region (T<170 K) shows a near constant susceptibility of 1.5×10−4 emu/g. Between 170 and 225 K there is a dip in the susceptibility. For T≳225 K the susceptibility decreases with temperature in accord with the Curie Weiss law. We have estimated the Neel temperature to be 220 K from the peak in the magnetic susceptibility and the collapse of the magnetic hyperfine splitting in the Mossbauer data. While the film discussed in the present paper is amorphous, we have found that films sputtered at slightly higher power levels consist of microcrystals of γFe2 O3.
TL;DR: In this article, the magnetic properties of a U3X4 were discussed in the frame-work of the molecular field approximation, applied to the model proposed previously, which contains a three-axial single-ion anisotropy.
Abstract: The magnetic properties of a ferromagnet such as U3X4 are discussed in the frame-work of the molecular-field approximation, applied to the model proposed previously, which contains a three-axial single-ion anisotropy. Using the perturbation method in the vicinity of the Curie point, the Curie temperature, the magnetic ordering and the paramagnetic susceptibility are calculated. The spontaneous magnetisation as a function of the temperature is also determined.
TL;DR: In this paper, low-field magnetic susceptibility and the magnetic field dependence of magnetization of Metglas 2605 A (Fe78Mo2B20) were studied between 300 and 600 K and in fields up to 10kG.
TL;DR: In this article, a SQUID magnetometer has been used to measure the temperature dependent magnetization of two dilute alloys of Mn in Pd. This dilute alloy system displays a remarkable variation in its properties.
Abstract: A SQUID Magnetometer has been used to measure the temperature dependent magnetization of two dilute alloys of Mn in Pd. Results are presented for temperatures T of 0.01 to 1 Kelvin, for applied magnetizing fields Ha of 0.5 to 600 Oe, for samples containing 255 and 575 atomic ppm of Mn. This dilute alloy system displays a remarkable variation in its properties. For the concentration region under study, PdMn may be described as a giant‐moment spin glass. (1) At low field and high temperature, the magnetization M follows a Curie‐Weiss law, M = CHa/ (T−ϑ), with positive (ferromagnetic) ϑ values of 31 and 78 mK, respectively. From the Curie constant we obtain a ’’giant’’ effective moment per Mn impurity, p of 11 μB (μB = Bohr magneton). With spin S = 5/2, this gives an effective g value of g = 3.7. (2) From the highest field data we estimate the saturation moment per Mn spin gSμB to be 9 μB; with S = 5/2, this gives g = 3.6 in good agreement. (3) As the temperature is lowered in constant applied field the magn...